Fix listing of '' and '/'.

runtime/bin/directory_linux.cc

Index: runtime/bin/directory_linux.cc
diff --git a/runtime/bin/directory_linux.cc b/runtime/bin/directory_linux.cc
index 3b9d01684286fc31c79d06561168d19f24364a8f..c37b58b1ebd42179b52212eb7198bd0f107deca8 100644
--- a/runtime/bin/directory_linux.cc
+++ b/runtime/bin/directory_linux.cc
@@ -80,11 +80,6 @@ ListType DirectoryListingEntry::Next(DirectoryListing* listing) {
   }
 
   if (lister_ == 0) {
-    if (!listing->path_buffer().Add(File::PathSeparator())) {
-      done_ = true;
-      return kListError;
-    }
-    path_length_ = listing->path_buffer().length();
     do {
       lister_ = reinterpret_cast<intptr_t>(
           opendir(listing->path_buffer().AsString()));
@@ -94,6 +89,12 @@ ListType DirectoryListingEntry::Next(DirectoryListing* listing) {
       done_ = true;
       return kListError;
     }
+    if (parent_ != NULL) {
+      if (!listing->path_buffer().Add(File::PathSeparator())) {
+        return kListError;
+      }
+    }
+    path_length_ = listing->path_buffer().length();
   }
   // Reset.
   listing->path_buffer().Reset(path_length_);